The present invention relates in general to a writing instrument and more particularly to a writing instrument nib which has an ink feeding groove or grooves on the outer surface thereof. Further, the present invention relates to a writing nib, the outer surface of which is converged toward a writing point thereof.
A known nib of the type described above is, for example, a nib made of a synthetic resin which is formed by extrusion molding, cutting to a predetermined length and shaping the cut portion. The synthetic resin nib has various shapes such as a conical shape, cannon-ball shape having a tapered or converged end for a writing point.
The synthetic resin nib has ink feeding channels or passages. Some resin nibs have an ink passage or passages at a longitudinally central portion thereof, and others do not have a passage or passages at the central portion thereof. The latter type of nib provides more desirable mechanical strength properties since a writing point of the nib is formed by the resin material at the central portion. In addition, the resin nib provides a desired resiliency so that a larger area of the writing point contacts a paper or the like.
However, one of the most serious problems inherent in the synthetic reisn nib is its poor wearing property.
A representative example of a nib having a remarkable resistance to wear is a ceramic nib, which is conventional and is disclosed in, for example, Japanese Patent Publication No. 26-5511 published in 1951.
However, a problem which still remains with this type of ceramic nib is that it is unreliable since it lacks flexibility and it is difficult to prevent foreign particles from becoming blocked in the ink channels of the nib.
Recently, a new type of ceramic nib has been proposed which is cylindrical and has a central aperture for an ink channel with a pin or a longitudinal element which is slidably inserted into the ink channel to thereby overcome the problem the ink channel due to blocking of foreign particles. This type of cylindrical is more reliable in ink feeding but still has a problem in that it is rather difficult to produce a thin tubular nib for a thin or slender writing.